The temperature in several parts of Kerala rose on Tuesday but on Wednesday evening, dark clouds formed at many places, suggesting possible rains. An IMD official forecast rains across Kerala in the next 24 hours.

Fishermen have been warned about winds blowing 45 to 55 km an hour on the coast. Weather officials are analysing the data recorded at 14 weather stations located at the Lakshadweep, Kerala and Mangalore in Karnataka.

The onset of monsoon is declared on the basis of amount of rain received at these 14 stations. Wind and cloud formations are other indicators.

Pre-monsoon showers continued in Andhra Pradesh and Telangana on Wednesday, further bringing down the day temperature, Met officials said.

Up in the north, moderate rain in various parts of Himachal Pradesh on Wednesday brought down the temperature by two to three notches, with the weatherman forecasting more thunder showers in the state on Thursday.

In the east, Kolkata had a hot and oppressively humid day on Wednesday, even as the weatherman predicted thunderstorms over the next 48 hours at a couple of places of Gangetic West Bengal, covering the districts in the southern part of the state.

The heat and humidity inconvenienced those out on the streets, while ice cream sellers and cold drink stalls made a killing. "There is no rainfall prediction over the next 24 hours. But there is possibility of thunder showers at a couple of places in Gangetic west Bengal in the next 48 hours," an official at the Regional Meteorological Office, Alipore.